Switching power supply unit

ABSTRACT

Replaceable parts having a relatively short service life such as electrolytic capacitors are mounted on a reusable printed circuit board and one or more than one replaceable printed circuit boards so that the operation of replacing the electrolytic capacitors can be performed very easily and reliably. The replaceable printed circuit board may preferably be fitted to a replaceable frame and the replaceable frame is replaced. The primary side replaceable parts and the secondary side replaceable parts may be mounted on the same replaceable printed circuit board.

TECHNICAL FIELD

This invention relates to recycling of switching power supply units.More particularly, the present invention relates to replacement of partsof switching power supply units.

BACKGROUND ART

People have been increasingly paying attention to recycling ofelectronic parts in recent years because of environmental concerns.Particularly, recycling of printed circuit boards of electronic productssuch as personal computers and printers is a very serous problem to bedissolved.

Circuits that need recycling include power supply circuits. Power supplycircuits normally contain electrolytic capacitors. Electrolyticcapacitors have only a short service life if compared with otherelectronic parts. In addition, generally in a power supply circuit,electrolytic capacitors are arranged close to parts generating a largeamount of heat and therefore, the service life of electrolyticcapacitors can be further shortened by such heat. If there is somethingwrong with an electrolytic capacitor contained in an electronic product,it can seriously affect other electronic parts surrounding it.Therefore, electrolytic capacitors and other electronic parts havingonly a short service life are manually replaced and the other electronicparts are reutilized by following procedure that includes the stepslisted below.

-   1. Visually confirm the electronic part to be replaced.-   2. Remove the solder between the electronic part to be replaced and    the printed substrate.-   3. Remove the electronic part to be replaced from the printed    substrate.-   4. A replacement electronic part is inserted into the printed    substrate.-   5. Solder the replacement electronic part to the printed substrate.-   6. Visually confirm the newly soldered replacement electronic part.

Meanwhile, Japanese Patent Application Laid-Open No. 6-61621 describes atechnique of functionally separating a plurality of circuit sections ona single printed circuit board so that only the circuit section that hasturned out to be defective can be replaced by a correspondingreplacement circuit section that is commercially available. JapanesePatent Application Laid-Open No. 6-61621 also describes that detachablepartitioning sections are arranged among the separated circuit sectionsand each of the circuit sections is provided with an interface.

However, the above described known technique of steps 1 through 6 forreplacing an electronic part such as an electrolytic capacitor isaccompanied by the following problems.

-   -   Tremendous time and efforts have to be spent in the steps for        replacing an electronic part.    -   Since the soldering operation necessary for replacing an        electronic part generates heat, means for protecting the        operator has to be provided.    -   The heat generated by the soldering operation necessary for        replacing an electronic part can peel off, if partly, the        circuit pattern and/or reduce the reliability of the circuit        pattern.    -   A wrong electronic part can be used as replacement at the time        of replacing an electronic part.    -   The polarities of the replacement electronic part can be        inverted at the time of replacing an electronic part.

In recent years, small packaged switching power supply units have beenfrequently used. The switching power supply unit is formed independentlyfrom the electronic product in which it is used and hence it is requiredto be replaced and reused in a simple and reliable way. Morespecifically, switching power supply units have to be so designed thatthe user can easily replace the switching power supply unit of his orher own electronic product.

With the technique described in the above cited Japanese PatentApplication Laid-Open No. 6-61621, the frame of the electronic productneeds to be opened and the printed substrate to be replaced has to beseparated from-the printed circuit board in the inside. Subsequently, areplacement printed substrate needs to be connected and the frame has tobe closed once again. Thus, the user may not feasibly use such atechnique.

DISCLOSURE OF THE INVENTION

In view of the above identified circumstances, it is therefore an objectof the present invention to provide a switching power supply unit thatcan be replaced and reused with ease by allowing any of its electronicparts including an electrolytic capacitor to be replaced in a simple andreliable way. Another object of the present invention is to provide aswitching power supply unit the user can safely replace.

According to the invention, the above objects are achieved by providinga switching power supply unit comprising a reusable printed circuitboard carrying reusable electronic parts and a replaceable printedcircuit board carrying replaceable electronic parts and formed so as tobe removably fitted to the reusable printed circuit board, thereplaceable printed circuit board being electrically and mechanicallyconnected to the reusable printed circuit board.

Preferably, in a switching power supply unit as defined above, saidreusable printed circuit board is fitted to a main body frame and saidreplaceable printed circuit board is fitted to a replaceable frame insuch a way that said mechanical connection is realized by way of saidmain body frame and said replaceable frame.

Preferably, in a switching power supply unit as defined above, saidreusable printed circuit board and said replaceable printed circuitboard are provided with respective connectors in such a way that saidelectronic connection is realized by way of said connectors.

Preferably, in a switching power supply unit as defined above,replaceable printed circuit boards are provided respectively at theprimary side and at the secondary side of the unit.

Preferably, in a switching power supply unit as defined above, thereplaceable electronic parts provided at the primary side and thereplaceable electronic parts provided at the secondary side of the unitare mounted on the same replaceable printed circuit board.

Preferably, in a switching power supply unit as defined above, thereplaceable electronic parts provided at the primary side and thereplaceable electronic parts provided at the secondary side as mountedon the same replaceable printed circuit board are arranged with apredetermined gap interposed between them.

Alternatively, in a switching power supply unit as defined above, thereplaceable electronic parts provided at the primary side and thereplaceable electronic parts provided at the secondary side may bearranged along a lateral side of the switching power supply unit.

Preferably, in a switching power supply unit as defined above, saidreplaceable electronic parts include an electrolytic capacitor.

The above and other objects of the invention will become more apparentfrom the following description taken in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic circuit diagram of the first embodiment ofswitching power supply unit according to the invention;

FIG. 2 is a schematic plan view of the power supply printed circuitboard of the first embodiment;

FIG. 3A is a schematic cross sectional view of the first embodiment ofswitching power supply unit according to the invention;

FIG. 3B is a schematic perspective view of the first embodiment ofswitching power supply unit according to the invention;

FIG. 4A is a schematic cross sectional view of the second embodiment ofswitching power supply unit according to the invention; and

FIG. 4B is a schematic perspective view of the second embodiment ofswitching power supply unit according to the invention.

BEST MODE FOR CARRYING OUT THE INVENTION

(First Embodiment)

FIG. 1 is a schematic circuit diagram of the first embodiment ofswitching power supply unit according to the invention and FIG. 2 is aschematic plan view of the power supply printed circuit board preparedby embodying the circuit of FIG. 1.

In FIGS. 1 and 2, reference symbol 1 generally denotes a power supplyprinted circuit board. Main electronic parts that are used for the powersupply printed circuit board 1 include a switching element 2, atransformer 3, a rectifier diode 4 and electrolytic capacitors 5, 6. Thepower supply printed circuit board 1 comprises a reusable printedcircuit board 7 that does not require replacement of any electronic partthereof because it is to be put to reuse. The reusable printed circuitboard 7 carries a switching element 2, a transformer 3, a rectifierdiode 4 and so on that have a long service life and are not liable toget out of order.

The power supply printed circuit board 1 also comprises a secondary sidereplaceable printed circuit board 8 carrying electrolytic capacitors 5that have relatively short service life and are relatively liable to getout of order. A connector 10 is formed on the reusable printed circuitboard 7, whereas a connector 11 is formed on the secondary sidereplaceable printed circuit board 8. The reusable printed circuit board7 and the secondary side replaceable printed circuit board 8 come to beelectrically connected to each other by connecting the connectors 10,11. The connectors 10, 11 are removably fitted to the respective printedcircuit boards 7, 8 so that the secondary side replaceable printedcircuit board 8 can be easily moved away from the reusable printedcircuit board 7.

Reference symbol 9 denotes a primary side replaceable printed circuitboard carrying an electrolytic capacitor 6 that has relatively shortservice life and is relatively liable to get out of order. A connector13 is formed on the reusable printed circuit board 7, whereas aconnector 12 is formed on the primary side replaceable printed circuitboard 9. The reusable printed circuit board 7 and the primary sidereplaceable printed circuit board 9 come to be electrically connected toeach other by connecting the connectors 12, 13. The connectors 12, 13are removably fitted to the respective printed circuit boards 7, 9 sothat the primary side replaceable printed circuit board 9 can be easilymoved away from the reusable printed circuit board 7.

When the electrolytic capacitors 5, 6 of the secondary side replaceableprinted circuit board 8 and the primary side replaceable printed circuitboard 9 respectively go out of service life and have to be replaced,firstly the connectors 10, 11 and the connectors 12, 13 are disconnectedfrom each other and the secondary side replaceable printed circuit board8 and the primary side replaceable printed circuit board 9 are movedaway from the reusable printed circuit board 7. Then, a new secondaryside replaceable printed circuit board 8 and a new primary sidereplaceable printed circuit board 9 that are prepared in advance arefitted to said reusable printed circuit board 7 by connecting theconnectors 10, 11 and the connectors 12, 13 to each other.

FIGS. 3A and 3B schematically illustrate the first embodiment ofswitching power supply unit realized by using the power supply printedcircuit board 1 described above by referring to FIGS. 1 and 2. FIG. 3Ais a schematic cross sectional view of the first embodiment of switchingpower supply unit 100 and FIG. 3B is a schematic perspective view of thefirst embodiment of switching power supply unit 100. Note that thereplaceable parts are exploded in FIGS. 3A and 3B for the purpose ofeasy understanding. The inside of the switching power supply unit 100 ismade partly visible. In FIGS. 3A and 3B, the components that are same asthose of FIGS. 1 and 2 are denoted respectively by the same referencesymbols and will not be described any further.

In the switching power supply unit 100, reference symbol 19 denotes amolded main body frame to be used for containing the switching powersupply unit 100. The reusable printed circuit board 7 is mounted on thebottom of the main body frame 19. Reference symbol 20 denotes a moldedsecondary side replaceable frame to which the secondary side replaceableprinted circuit board 8 that carries a plurality of electrolyticcapacitors 5 is integrally fitted. Engaging projections 22, 23 areformed on the secondary side replaceable frame 20, whereas correspondingrespective engaging recesses 24, 25 are formed on the main body frame19. The secondary side replaceable printed circuit board 8 is arrangedin such a way that the connector 11 of the secondary side replaceableprinted circuit board 8 and the connector 10 of the reusable printedcircuit board 7 are electrically reliably connected to each other whenthe engaging projections 22, 23 of the secondary side replaceable frame20 and the corresponding respective engaging recesses 24, 25 of the mainbody frame 19 are brought into mutual mechanical engagement.

Reference symbol 21 denotes a molded primary side replaceable frame towhich the primary side replaceable printed circuit board 9 carrying theelectrolytic capacitor 6 is integrally fitted. In addition to theelectrolytic capacitor 6, a photocoupler 14 having a service lifesubstantially same as that of the electrolytic capacitor 6 and a fuse 15that will probably be broken when the electrolytic capacitor 6 gets outof order are also mounted on the primary side replaceable printedcircuit board 9. Engaging projections 26, 27 are formed on the primaryside replaceable frame 21, whereas corresponding respective engagingrecesses 28, 29 are formed on the main body frame 19. The primary sidereplaceable printed circuit board 9 is arranged in such a way that theconnector 12 of the primary side replaceable printed circuit board 9 andthe connector 13 of the reusable printed circuit board 7 areelectrically reliably connected to each other when the engagingprojections 26, 27 of the primary side replaceable frame 21 and thecorresponding respective engaging recesses 28, 29 of the main body frame19 are brought into mutual mechanical engagement.

When the electrolytic capacitors 5, 6 go out of service life and have tobe replaced, firstly the secondary side replaceable frame 20 and theprimary side replaceable frame 21 are moved away from the main bodyframe 19 by releasing the engaging projections 22, 23, 26, 27 and thecorresponding respective engaging recesses 24, 25, 28, 29 from mutualengagement. Then, a new secondary side replaceable frame 20 and a newprimary side replaceable frame 21 that are prepared in advance arefitted to the main body frame 19 by bringing the engaging projections22, 23, 26, 27 and the corresponding respective engaging recesses 24,25, 28, 29 into mutual engagement.

With the above described arrangement, the electrolytic capacitors 5, 6can be replaced with easy in the switching power supply unit 100. Thestrength of each of the replaceable parts can be raised because theelectrolytic capacitors 5, 6 can be replaced simply by replacing thesecondary side replaceable frame 20 and the primary side replaceableframe 21. Therefore, the switching power supply unit can be handled inan easy, safe and reliably manner and the user can replace thereplaceable printed circuit boards.

Additionally, not only the electrolytic capacitors but also theelectronic parts having a service life substantially same as that of theelectrolytic capacitors such as the photocoupler 14 and the fuse 15 thatcan get out of order with the electrolytic capacitors may be mounted onthe replaceable printed circuit boards.

(Second Embodiment)

Now, the second embodiment of the invention will be described below byreferring to FIGS. 4A and 4B. FIG. 4A is a schematic cross sectionalview of the second embodiment of switching power supply unit 200 andFIG. 4B is a schematic perspective view of the second embodiment ofswitching power supply unit 200. Note that the replaceable parts areexploded in FIGS. 4A and 4B for the purpose of easy understanding. Theinside of the switching power supply unit 200 is made partly visible. InFIGS. 4A and 4B, the components that are same as those of FIGS. 3A and3B are denoted respectively by the same reference symbols and will notbe described any further.

The embodiment of FIGS. 4A and 4B differs from that of FIGS. 3A and 3Bin that the secondary side replaceable printed circuit board 8 and theprimary side replaceable printed circuit board 9 of the first embodimentare put together and formed as a single replaceable printed circuitboard 30 in the second embodiment. All of the secondary sideelectrolytic capacitors 5, the primary side electrolytic capacitor 6,the photocoupler 14 and the fuse 15 are mounted on the replaceableprinted circuit board 30. Since the electrolytic capacitors have asubstantially same service life, the secondary side electrolyticcapacitors 5 and the primary side electrolytic capacitor 6 arepreferably replaced at the same time. From this point of view, thesecond embodiment is so designed that the secondary side electrolyticcapacitors 5 and the primary side electrolytic capacitor 6 can bereplaced in an easy, safe and reliably manner.

The replaceable printed circuit board 30 is fitted to a replaceableframe 31. As in the case of the secondary side replaceable frame 20 andthe primary side replaceable frame 21, engaging projections 22, 23, 26,27 are formed on the replaceable frame 31, whereas correspondingrespective engaging recesses 24, 25, 28, 29 are formed on the main bodyframe 19. The connectors 10, 11 and the connectors 12, 13 aremechanically linked to each other and the replaceable printed circuitboard 30 and the reusable printed circuit board 7 are electricallyconnected to each other when the engaging projections 22, 23, 26, 27 andthe corresponding respective engaging recesses 24, 25, 28, 29 arebrought into mutual engagement.

This embodiment has to be so designed in advance that the secondary sideelectrolytic capacitors 5 and the primary side electrolytic capacitor 6can be arranged along the same lateral side of the switching powersupply unit 200 because they are mounted on the same replaceable printedcircuit board 30.

Additionally, since the primary side and the secondary side of a powersupply circuit normally need to be insulated from each other, thesecondary side electrolytic capacitors 5 and the primary sideelectrolytic capacitor 6 have to be mounted with a sufficient distanceseparating them from each other when they are mounted on the samereplaceable printed circuit board 30.

With the above described arrangement, the electrolytic capacitors 5, 6can be replaced simply by replacing the replaceable frame 31 of theswitching power supply unit. Therefore, this embodiment can be handledmore easily than the first embodiment and hence the user can easilyreplace the replaceable printed circuit board.

As described above in detail, according to the invention, replaceableparts having a relatively short service life such as electrolyticcapacitors are mounted on a reusable printed circuit board and one ormore than one replaceable printed circuit boards so that the operationof replacing the electrolytic capacitors can be performed very easilyand reliably. Then, as a result, the labor cost, the number of steps andthe time period that have to be spent for the operation of replacing theelectronic parts can be remarkably reduced.

The operation of replacing the electrolytic capacitors can be performedmore easily and reliably when the replaceable printed circuit board isfitted to a replaceable frame and the replaceable frame is replaced.Then, the user can easily replace the electrolytic capacitors.

The operation of replacing the electrolytic capacitors can be performedmore easily and reliably when the primary side replaceable parts and thesecondary side replaceable parts are mounted on the same replaceableprinted circuit board.

1. A switching power supply unit comprising: a reusable printed circuitboard carrying reusable electronic parts; a main body frame carryingsaid reusable printed circuit board; a replaceable printed circuit boardcarrying replaceable electronic parts and formed so as to be removablyfitted to said reusable printed circuit board; and a replaceable framecarrying said replaceable printed circuit board; the replaceable printedcircuit board being electrically and mechanically connected to thereusable printed circuit board and adapted to be replaced by removingsaid replaceable frame.
 2. The switching power supply unit according toclaim 1, wherein: said replaceable printed circuit board being adaptedto be replaced with another replaceable printed circuit board carried byanother replaceable frame previously prepared.
 3. The switching powersupply unit according to claim 1, wherein said reusable printed circuitboard and said replaceable printed circuit board are provided withrespective connectors in such a way that said reusable printed circuitboard and said replaceable printed circuit board are electricallyconnected by connecting the connectors.
 4. The switching power supplyunit according to claim 1, wherein the replaceable printed circuitboards are provided respectively at the primary side and at thesecondary side of the unit.
 5. The switching power supply unit accordingto claim 1, wherein the replaceable electronic parts provided at theprimary side and those provided at the secondary side of the unit aremounted on the same replaceable printed circuit board.
 6. The switchingpower supply unit according to claim 5, wherein the replaceableelectronic parts provided at the primary side and the replaceableelectronic parts provided at the secondary side as mounted on the samereplaceable printed circuit board are arranged with a predetermined gapinterposed between them.
 7. The switching power supply unit according toclaim 5, wherein the replaceable electronic parts provided at theprimary side and the replaceable electronic parts provided at thesecondary side are arranged along a lateral side of the switching powersupply unit.
 8. The switching power supply unit according to claim 1,wherein said replaceable electronic parts include at least anelectrolytic capacitor.
 9. The switching power supply unit according toclaim 8, wherein said replaceable electronic parts further include aphotocoupler and a fuse.